1. Field of the Invention
The present invention relates to a color signal generation circuit related to on-screen displays for a home-use VCRs or the like and, in particular, to a color signal generation circuit for coloring internally prepared displays.
2. Description of the Related Art
FIG. 1 shows a conventional color signal generation circuit for use in internally preparing display pictures. This circuit comprises a color signal generation circuit 4, a divider 1, and a shift circuit 2. The color signal generation circuit 4 generates eight color signals having phases shifted in 45.degree. steps. The divider 1, comprising flip flops 1a, 1b, divides a 4fsc subcarrier whose frequency is four times that of a color burst signal (wherein 1 fsc is 3.58 MHz in NTSC), into a plurality of divided signals. The shift circuit 2 shifts the phases of divided signals outputted by the divider 1, in accordance with a clock signal supplied via an inverter 3.
As a result of the functions of the divider 1 and the shift circuit 2, eight signals with various phases, namely .phi.0 to .phi.7 in FIG. 2, are generated. Six out of the eight generated signals are input into respective delay circuits 11 to 16, which then delays received signals as required to adjust their phases so that they correspond to desired colors. FIG. 2 shows waveforms of various signals.
According to a circuit as shown in FIG. 1, it is possible to generate a plurality of color signals because a 4fsc signal is divided into signals with phases shifted in 45.degree. steps, and the resulting signals are delayed so as to correspond to desired colors.
The above color signal generation circuit, however, has a problem in that it requires a dedicated circuit for every color. As a delay circuit often requires a capacitor and cannot be easily integrated into an IC circuit, provision of dedicated circuits for all colors increases costs.